1. Field of Invention
The present invention relates generally to a fitting assembly for composite pressure vessels and, more specifically, to a fitting assembly for filament-reinforced composite pressure vessels and methods of forming the same.
2. Description of Related Art
Reinforced pressure vessels are preferred for use in many fluid-containment applications because they are substantially lighter in weight than pressure vessels formed of traditional materials such as steel, and provide exceptional mechanical strength and corrosion resistance. The term “fluid” refers to any material or substance that changes shape or direction uniformly in response to an external force imposed on it and includes not only liquids, but also gases and finely divided solids.
The vessel wall of a filament-reinforced plastic pressure vessel is substantially continuous, and is formed of a composite laminated structure. The inner portion or layer of the vessel wall is typically a thermoplastic liner having an inner surface and an outer surface. The outer portion or layer of the vessel wall is typically formed of overlapping helically-wound reinforcing glass filaments that are wet-wrapped with thermoset plastic and bonded to the outer surface of the thermoplastic liner.
As is the case with all fluid-containment vessels, the aforementioned conventional thermoset and thermoplastic composite pressure vessels need at least one port, and frequently several ports, for providing access to fill and/or empty the vessel and/or for permitting the attachment of devices that monitor the pressure and/or other conditions within the interior of the vessel. These ports are commonly provided as rigid fittings that are adapted to connect to hoses, pipes and/or measurement equipment (e.g., pressure sensors and gauges).
Unfortunately, a port cannot usually be added to the aforementioned conventional thermoset and thermoplastic pressure vessel simply by drilling or cutting a hole in the vessel wall and bonding a port structure around the hole (or vice versa). It is commonly believed that, unless the port structure is bonded to the thermoplastic liner and the thermoset and filament reinforced outer layer, the mechanical strength of the pressure vessel is substantially weakened. Moreover, in conventional vessels, severing the continuous filament reinforcement undermines the strength of the vessel.
Therefore, there exists a need in the art for an improved composite pressure vessel, and for a method for forming a port in a sidewall thereof. There further exists a need in the art for a fitting assembly that is adapted to be efficiently secured to the pressure vessel so as to define a port therein.